Accelerating device for alternating-current motors.



ACGELERATING W. D. LUTZ. DEVICE PoR ALTBRNATING CURRENT MOTORS.

APPLICATION FILED JAN. 7, 1911.

Patented Nov. 24, 1914.

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W. D. LUTZ. AGGBLERATING DEVICE POR ALTBRNATING CURRENT MOTORS.

APPLICATION FILED JAN.7, 1911. 1, l 18,296.

Patented Nov. 24, 1914.

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:.Urz, or -ALLENDALE conocen,

PAtrENfr OFFICE- rNEW JERIEY, ASSIGNOR T OTB ELEVATOR OIOMPANY, 0E JERSEY. CITY. NEWJEBBEY, A CORPORATION 0F NEW JERSEY.

\ LUOELEMTING DEVICE FOR ALTERNATING-OURRENT MOTORS.

To. all who/m, it may concern "lle it known that I, WILLIAM D. Ln'rz,.a citizen of the United States, residing in the borough of Allendale in the county of B ergen and State `of ew Jersey, have 1nvented a new and useful' Improvement in Accelerating Devices for 'Alternating-Current Motors, of which the following is a specification. A

My invention relates to motor control, more "particularly to the acceleration oi 'alternating' current motors. I

Electro-'magnets are frequentlyemployed to effect the acceleration ot motors, but some diiiiculty is experienced in rendering alternatina` current magnets dependent for eration upon the speed of the motor. In general thepulll of an alternating current magnet varies directly with the voltamperes and inversely as the frequency of thecnergizing current. 'lhat is, with an impressed voltage of'a given value and a riven number et turns in "the magnet winfings, the pull is greatest tfor the and decreases with an increase in frequency. When the voltage and frequency are constant, the pull varies inversely asthe number of turns. v

vAn obiect of my invention is to provide improver. means to accelerate a motor, and this to be accomplished by a current 'of a frequency varying inversely as the speed of the yn`1otor,. together with electro-responsive apparatus operated und controlled by said current.' In the accuunpanying drawings, Figure 1 shows 'ancmbodinient of mv i connection with a motor: Fig. 2 is simi lar to Fig. 1 except that magnets with different numbers of turns are employed; Fig. ii-shows'a modification to change the potential applied to a rectiyinf or frequency changingicounnutator; Fie'. Fis a modification of a part of Fig. 2.

' 'Referring now to Figa-'1 an alternating crrent motor M is shown having a slipring-'connection for 'an accelerating resist.- ance IR. An accelerating magnet A receives-current -from a frequency chanr C attached .to the shaft of the motor or ldriven by it, Amain switch S is to connect the-motorto the supply mains. f .:i` he. frequency changer C comprises contact ringer 12, 18, which arey cdnnectedby A. lpeaiiloltion o! Letten Patent. Application nica January 7,

lowest frequency set of invention VIin Patented Nov. 24,A 10.14. 1811. lerici No. 801,426.

conductors 14,15 to the motor leads 10. 11. e commutator bars lil are connected alternately to the contact rings 12, 18 and the brushes 17, 18, which are so spliced as to be connected through the connnutator bars to opposite rin rs 12, lil, provide collectorfterminals for tie rectified current which is led by conductors 1S), 2() through the magnet winding 2i of the accelerating magnet W hen the commutator is at rest the current .applied to the accelerating magnet W'indin is ot' the sume frequency as that applied to the motor leads l0 and 11, because the terminals .'19, 20 have a direct electrical conncction through the slip rings and commutator bu rs with the leads 1Q and ll. As the speed of the commutator'is increased the frequency in the rectified circuit becomes less und less until at `full no slip, the 'frequcncycin the rcctiliedcircuit would be zero or some predetermined` frequency lower than the frequency applied to the motor leads and ll. Obviously the frequency ot' the current supplied to the accelerating,r magnet is gradually reduced as the speed oie the motor increases, because cach time the brushes 17, 1S, pass from one `comn'iuimtor bars to the next the cirspecd, it there were l cuit connections are reversed and neutralize a phase reversal. As the ,motor accelerates the number of phase reversals that are thus neutralized is gradually increased, or in other words, the -rerpicncy oi the current supplied-T to ythe .accelerating magnet is gradually' decreased. The pull of an alter- 11a-ting current magnet increases as the frequency decreases, sd the pull of the magnet A yis greatest when the ulls eed. Groups of contacts, as a. 71,0, and l are provided in connection with the accelerating magnet andthe distances of the movable parts are so proportioned that the group of contacts are joined in the order named. Portions of the sectional resistance 'R, which is connected to `the secondary winding of the motor, through the sliprings 22,' 23, 24, are short-circuited in succession to accelerate the motlr.y f

nFi 2,.the same ,arrangement of the motor lt, commutator C andfresistance R, is shown, andL a .plurality-"lof accelerating magnets-.having different numbers of turns, ins ad of a single' accelerating. ma jet. Th magnet' wndings2', 126,!27 an `28 tor fio

are lconnected in parallel across the rectified current mains 19, 20'. Of these magnets, the first has only theiaccelerating contacts 29, while' the others control the contacts 30,

32, as well as the breakingl contacts 33,34 and 35, respectively; when. one ofthe latter magnets is energized land operated, it breaks the magnet winding circuit for the magnet previously operated.

The operation of is dependent upon the alternating current from the commutator C', and Asince the magnets are all connected in parallel at' the start, the magnet which has the least number of turns exerts the greatest pull. In the present embodiment the contacts 29 are first joined, short circuitin a portion of the starting resistance R, This causes the mo tor to be accelerated and the frequency of the current from the commutator is reduced. The second magnet winding 26 now receives more energizing current and tion of its core, contacts 30 are joined and the breaking contacts 33 separated. The action of the magnet 26 short circuits another portion. of the sectional resistance R, and breaks the circuit through the magnet winding 25. In a similar' manner the other magnets operate to short-circuit additional portions of the starting resistance and to open the circuit of the previously operated mag net. At full speed the secondary resistance of the motor-is all short-circuited.

When the potential of the commutator circuit is too low or too high transformer may be inserted' in the c1rcu1t leading to the commutator C as shown by Fig.' 3. In'

this figure is shown'a primary winding 39 wound on a transformer core nected by the conductors 37, 38, tothe motor leads 11, 10, respectively, winding 40 with conductors 14, 15, connecting it to the slip-rings 12 and 13.A By this means the potential applied to the accelerating magnet or magnets may be changed to any desired degree.

Fig. 4 shows as a modification an arrangement whereby the magnets 25', 26', 27 and 28 receive energizing current from the commutator current leads 19 and 20 and are operative to close energizing circuits, in suc# cession, to the magnet windings 41, 42, 43 and 44, respectively from the mains 45 and 46 which are connected to the same source of supply as the motor. The magnets of these latter windings are operative to close the short-circuiting contacts 29, 30', 31 and 32 in succession to accelerate the motor. The advantage of this arrangement is that the magnets energized by frequency changerare small compared with the main magnets and takebut little current from the rectifier. Various other modifica-- tions are equally obvious.

It is evident that my accelerating device the accelerating` magnets I 4being dependent upon their energization by the op'era- 36 and con-- and a secondary tacts,

' energizing means, and a frequency changer to supply a s the circuit from the is entirely automatic, requirin ".n atten-l tion, and is proof against care essand incompetent attendants. I desire not-to be limited to the exact construction` described, as those skilled in the arts to lwhich this application relates may make various changes without departing from the spirit or scope thereof.

What I claim is 1. An electro-magnetic motor accelerating device comprising a plurality of successively operable electro-responsive parts,

the successive operation of the said parts by a current of constant potential and variable frequency.

2. A'n electro-magnetic motor acceleratxing 'device having movable contacts and dependent for cnergization upon a current of( constant potential and variable frequency.

3. An electro-magnetic motor accelerating device having movable contacts and dependent for operation of the contacts in succession vupon a current of uniform impressed electromotive force and variable frequency.

4. A motor accelerating device compris` ing electro-magnets with windings of different numbers of turns, dependent for operation in regular successlon-upon a current of constant impressed voltage and variable frequency.

. 5. A motor accelerating device comprising electro-magnets with windings of differentnumbers of turns dependent for operation in regular succession upon a current ofguniform pressure4 and decreasingl frequency. l

6, In a motor accelerating device, the combination of movable contacts, electromagnets ,operatively energized .by currents of diiferentfrequencies to operate the conand lmeans to supply a constant potential current of variable frequency to vener zethe magnets in succession.

The combination with a motor of contacts operable by magnets having different numbers of winding turns', supply 'constant pot ntial current of decreasing frequency to energize thev magnets in succession to control the motor.

8. The combination with a motor of movable contacts, .electro-responsive means to operate the contacts, means to change the circuits of the electro-responsive current of variable frequency to energize the electro-responsive means in succession to control the motor.

9. The combination with a motor of movable contacts, electro-responsive devices to operate the contacts, a frequency changer to supply a current of variable frequency to energize the electro.- responsive devices in regular succession to control the motor, and

and a device to means in connection with the electro-responsivev devices to `render the device previously operated ineffective.

10. The combination with a motor of electro-responsive magnets with windings of different numbers of turns and in parallel, a frequency changer to supply a current of variable frequency to energize the said devices in regular eration` of the motor, and back contacts in connection with the magnets to open the winding circuit of the magnet previously energized.

1l. The combination current motor, of a frequency changer, resistance for the motor, and electr0responsive devices energized in succession by current of varying frequency from the said frequency changer to short-circuit portions of the resistance as the speed of the motor increases. y

12. The combination with an alternating current motor, of a frequency changeroperated by the motor, and electro-magnets having windings of different numbers of turnsenergized in succession said frequency changer creasing as the speed of the motor increases.

18. The' combination with an alternating current motor, of a frequency changer receiving current from the motor supply mains and operated by the motor, a plurality of electro-magnets connected in parallel having magnet windings of different numbers of turns receiving current and energized in succession by the current from the frequency changer, and means in connection with the magnets to vary the effective number of turns each time a magnet is energized after the first magnet is energized.

14. The combination with an alternating current motor having slip-ring secondary connections, of a frequency changer receiving current from the supply mains operated y the motor and producing a current of a frequency decreasing as the motor speed increases, a sectional resistance connected to the secondary winding of the motor by means of the slip-rings, electro-magnets hav'- by .current from the of a frequency desuccession to effect the accela frequency changer operated by withan alternating ing windings of different numbers of turns receiving energizing current from the frequency changer and operative in succession as the frequency decreases, contacts closed by the magnets effective to short-circuit portions of the sectional resistance to accelerate the motor, and back contacts on all of the magnets but the one first energized and effective when operated to open the winding of the magnet previously energized.

5. In an accelerating device, the combination with an alternating current motor, of the motor, and an electro-magnetic device with a plurality of electro-responsive parts receivin current from the frequency changer and dependent for energization upon a current of varying frequency delivered by the frequency changer.

16. The combination of an alternating current motor, a frequency changer operated thereby, electro-responsive devices operable in succession by current of varying frequency from the frequency changer.

17. The combination of an electric motor, electro-responsive devices operable in succession, and a frequency changer controlling such operation.

18. The combination of an electric motor, electro-responsive speed controlling devices, and a frequency changer supplying current of varying frequency to said devices.

19. The combinatlon of an electric motor, accelerating magnets, and a frequency changer driven by the motor and supplying current to the said magnets..

20. The combination of an electric motor, starting resistance, accelerating magnets, and a frequency changer driven thereby and supplying current to quency varying inversely as-the speed of the Imotor.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

WILLIAM D.v LUTZ.

Witnesses:

EDWARD H. STUT, GEORGE D. Rosa.

motor mains through the.

said magnet of a fre` 

